Severe stenosis of the cervical internal carotid artery was detected on magnetic resonance images in three patients from a series of eight with abnormality of flow. In contrast to complete loss of "flow void" in the horizontal carotid within the petrous bone seen in patients with complete occlusion, these three patients had partial flow void in which there was a central area of signal void in the artery, surrounded by circumferential increase in signal in the outer third of the artery. This was seen on axial views at right angles to the long axis of the artery below the petrous bone and on "in-plane" sections through the horizontal carotid canal. An animal model with 70% and 90% carotid stenosis and carotid occlusion was created. The model with 70% stenosis showed no significant change. The 90% stenosis model showed partial flow void in the center of the lumen with peripheral signal exactly as seen in the human patients.

Adipose tissue in the filum terminale is frequently associated with tethering of the spinal cord in patients with spina bifida occulta. We recently saw a patient with low back pain and no spina bifida occulta, in whom adipose tissue was noted in the area of the filum on an unenhanced computed tomographic (CT) scan. The patient had a tethered cord. This case suggested that, when CT scanning is done as the first imaging study in the evaluation of low back pain, fatty tissue in the area of the filum may be an indicator for tethering of the spinal cord. The present study was undertaken to determine the validity of using CT scan-detectable filal fat in the identification of possible tethered spinal cords among a group of patients experiencing low back pain. The presence of fat in the fila of 12 patients with the radiologically and histologically tethered cord syndrome was evaluated and the fila of 47 autopsied patients whose clinical history showed no back pain were examined histologically. There were accumulations of adipose tissue in the fila of 11 of the 12 (91%) patients with the tethered cord syndrome and in the fila of 9 of the 47 patients (17%) in the autopsy series. Of the 9 autopsy patients with fat in their fila, however only 3 patients (6%) exhibited collections of adipose tissue in the CT detection range (2 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

A retrospective study in 33 patients with intracranial meningioma demonstrates that two pathological mechanisms are involved in causing a hypodense area around the actual tumor: pressure-induced atrophy that persists after operation and true cerebral edema of unclear cause. The extent of the hypodense area is not related to tumor location or tumor size. A relationship between meningioma with a malignant tendency and the hemispheric spread of hypodensity can be observed.

Magnetic resonance images of 44 patients who had varying degrees of supratentorial signal abnormalities compatible with subcortical arteriosclerotic encephalopathy (SAE) were reviewed for posterior fossa findings. Brain stem lesions frequently accompanied supratentorial SAE and were seen as multiple, fairly symmetric areas of poorly defined, increased signal intensity on axial T2-weighted images. Involvement was generally confined to the central portions of the mid and upper pons. The typical appearance of brain stem involvement by SAE and its probable pathogenesis are reviewed.

Computed tomographic (CT) scans of ten patients with rhinocerebral mucormycosis were reviewed. Early paranasal sinus involvement appeared as mucosal thickening on CT scans, usually without air/fluid levels. Recognition as mucormycosis was facilitated by knowledge of the clinical setting or by identification of invasive disease. Evidence of bone destruction on CT scans was seen in only two patients, was a late finding, and usually was absent despite deep extension of disease beyond the bony confines of the paranasal sinus. Five cases had intracranial involvement, either as fungal abscess or infarction. Intracranial mucormycosis usually involved the base of the brain and cerebellum following invasion of the infratemporal fossa or orbit. Intracerebral fungal abscess appeared as low-density masses on CT scans, with variable peripheral enhancement and little surrounding vasogenic edema. Identification of a rim of spared cortex was useful in distinguishing infection from bland infarct. Serial CT scans were also useful in assessing response to hyperbaric oxygen treatment, surgery, and chemotherapy.

The mechanism of cavernous sinus involvement by metastatic carcinoma from a facial primary tumor is poorly understood. The lack of lymphatic and obvious direct extension implicate either a vascular or perineural method of spread. The authors describe four patients who exhibited cavernous sinus metastases from facial carcinoma, all of whom experienced cranial nerve symptoms before the diagnosis of cavernous sinus involvement was made. Furthermore, the pathologic specimens from these patients exhibited extensive perineural involvement. The authors propose that the mechanism of metastasis in these patients is perineural extension.

Three cases of catheter-induced inflammation are presented, two of which involved brain parenchyma and the ventricular system and one that involved the soft tissues of the scalp. All of the catheters were composed of natural rubber and had been in place for several years. Abnormalities seen on computed tomographic scans in these patients were variable but included mass effect, vasogenic edema, catheter destruction, calcification, and abnormal contrast enhancement of the parenchyma adjacent to the catheters. Certain features on the scans of the two patients with intracranial disease, however, were common to both cases, allowing the correct preoperative diagnosis to be made in the second patient encountered.

When patients present with spontaneous cerebrospinal fluid (CSF) rhinorrhea the primary diagnostic goal is localizing the site of leakage so that an appropriate approach for surgical repair can be selected. Metrizamide computed to­ mography (CT) has become the preferred method for inves­ tigating CSF rhinorrhea for several reasons [1-4]. CT provides superb bone detail so that fractures or areas of bony discon­ tinuity can be identified. If the patient is actively leaking at the time of the examination, opacified CSF can often be visualized directly as it passes through the fistula, providing the sine qua non for localization. CT also allows examination of the paranasal sinuses for evidence of air-fluid levels and abnor­ malities that may be associated with CSF rhinorrhea, such as hydrocephalus or empty sella. The most common sites of spontaneous CSF leak occur in the anterior fossa, sella, and parasellar regions, allowing communication with the paranasal sinuses or nasal fossa. The petro us bone is also a potential source of rhinorrhea via CSF carried by way of the eustachian tube [5]. We report a case of CSF rhinorrhea arising from a relatively uncommon site, the middle cranial fossa, accurately demonstrated by metrizamide CT and confirmed surgically. Bone/dura/arach­ noid defects at the floor of the middle fossa formed a fistula between the subarachnoid space and the pterygoid recess of the sphenoid sinus. Although such fistulae have been de­ scribed [6-9], they have not been demonstrated by metriza­ mide CT. Our case emphasizes the importance of examining the full lateral extent of the sphenoid sinus and appreciating the morphology of the middle cranial fossa floor when study­ ing patients with CSF rhinorrhea. The CT findings also lend credence to the hypothesis that middle fossa fistulae can be formed by spontaneous rupture of congenital "pits" at the skull base rather than as the result of previous trauma [8, 9].

A randomized double-blind study was performed in 27 patients to compare the clinical safety, incidence of pain and warmth, and film quality produced by iopamidol and Conray-60 in selective cerebral angiography. No complications or adverse reactions occurred in either group. Iopamidol was significantly less painful than was methylglucamine iothalamate for common carotid artery injections and caused significantly less heat in both common carotid and internal carotid artery injections. Film quality and diagnostic accuracy were excellent in both groups. These results, when viewed in conjunction with laboratory data demonstrating the decreased neurotoxicity of nonionic contrast agents, suggest that iopamidol is an important advance in the development of angiographic contrast media.